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Electronics · 2nd Puc Science

Ch 5Operational Amplifiers — 2nd PUC Electronics, concept-first.

The operational amplifier, almost always shortened to op-amp, is one of the most important building blocks in modern analog electronics, and it forms the heart of this chapter of the Karnataka 2nd PUC Electronics course.

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18

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13m

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Key concepts

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Common Mode Rejection Ratio (CMRR)

CMRR is the ratio of an op-amp's differential-mode gain to its common-mode gain, a measure of how well it amplifies difference signals while rejecting signals common to both inputs; it is usually expressed in decibels.

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Chapter contents

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Introduction

The operational amplifier, almost always shortened to op-amp, is one of the most important building blocks in modern analog electronics, and it forms the heart of this chapter of the Karnataka 2nd PUC…

5.1

Introduction

An operational amplifier (op-amp) is a direct-coupled, high-gain amplifier with high input impedance, low output impedance and high bandwidth, whose overall gain can be set precisely by external feedb…

5.2

Differential amplifier

The differential amplifier — also called the difference amplifier or emitter-coupled amplifier — is the main building block of IC amplifiers and is the basic input stage of an integrated op-amp.

5.3

Operational Amplifier

Having seen the differential amplifier at its input, we now look at the op-amp as a complete device through its AC equivalent circuit and its characteristics.

5.4

Applications of op-amp with negative feedback

The applications of an op-amp are broadly classified as linear and non-linear:

5.5

Op-Amp as summing amplifier

An op-amp summing amplifier produces an output equal to the sum of several input voltages. Because the op-amp is operated in the inverting mode, the output appears as the negative sum of the inputs, w…

5.6

Op-Amp as Differentiator and Integrator

This section covers two non-linear applications of the op-amp: the differentiator, whose output follows the derivative of the input, and the integrator, whose output follows the integral of the input.

5.7

Logarithmic and Anti-logarithmic amplifiers

A logarithmic amplifier produces an output proportional to the natural logarithm of the input voltage.

5.8

Active filters

Active filters use passive components (resistors and capacitors) together with active components (op-amps) to select a band of frequencies.

5.9

Digital to analog converter (DAC)

A Digital-to-Analog Converter (DAC) converts a digital input (binary, BCD or another digital code) into an analog output — usually a DC voltage — whose value is proportional to the binary number appli…

Chapter Summary

Operational Amplifiers — chapter summary

More questions

100 Q
+Show 8 questions8 questions
  1. Example 1If common mode gain and differential mode gain for a differential amplifier are 0.1 & 500 respectively, find CMRR in dB.Free
  2. Example 2Find the output voltage for the circuit shown in figure 5.4.7. ![An op-amp inverting amplifier. The input voltage \(V_i=3\text{ V}\) is appl…Free
  3. Example 3Find the output voltage for the circuit shown in figure 5.4.8. ![An op-amp non-inverting amplifier. The input \(2\text{ V}\) is applied to t…Free
  4. Example 4Find the output voltage for the circuit shown in figure 5.4.9. ![Two cascaded op-amp stages. Stage \(A_1\) is an op-amp inverter: \(V_i=3\te…Preview
  5. Example 5Find the output of the following circuit : ![An op-amp inverting adder (summing amplifier). Three inputs are applied to the inverting (\(-\)…Preview
  6. Example 6Find the output of the following circuit : ![A three-op-amp network. \(A_1\) is an inverting amplifier: input \(1\text{ V}\) through \(2\tex…Preview
  7. Example 7Design an op-amp circuit to realize the output, \(V_O = 3V_1-2V_2+V_3\), Assume \(R_F = 10\text{ k}\Omega\).Preview
  8. Example 8(a) Sketch the output of the following circuit, where \(V_i = 5\sin 100\pi t\).Preview
+Show 15 questions15 questions
  1. Q1Calculate the output voltage if \(V_1 = V_2 = 0.15\text{ V}\).Free
  2. Q2Determine the output voltage when \(V_1 = -V_2 = 1\text{ V}\).Free
  3. Q3Calculate the output voltage if \(V_1 = -0.2\text{ V}\) and \(V_2 = 0.1\text{ V}\).Free
  4. Q4Determine the output voltage for this circuit when a sinusoidal input of 2.5 mV is applied.Preview
  5. Q5Calculate the input voltage if the final output is 10.08 V.Preview
  6. Q6Calculate the output of the following circuit when \(V_1 = 25\text{ mV}\). ![Three cascaded op-amp stages (same circuit as Problem 5). Stage…Preview
  7. Q7Calculate the output voltage if \(V_1 = V_2 = 700\text{ mV}\).Preview
  8. Q8Calculate the output voltage if \(V_1 = 300\text{ mV}\) and \(V_2 = 700\text{ mV}\).Preview
  9. Q9Calculate the input voltage for this circuit if \(V_o = -11\text{ V}\).Preview
  10. Q10Calculate the input voltage when \(V_o = 11\text{ V}\).Preview
  11. Q11Calculate the output voltage.Preview
  12. Q12Calculate the cutoff frequency of a first-order low-pass filter for \(R_1 = 2.5\text{ k}\Omega\) and \(C_1 = 0.05\,\mu F\). Draw the circuit…Preview
  13. Q13Determine the output voltage when \(V_1 = -V_2 = -1\text{ V}\).Preview
  14. Q14How many op-amps are required to implement this equation? \(V_o = -\left(\dfrac{R_f}{R_1}V_1 + \dfrac{R_f}{R_2}V_2 + \dfrac{R_f}{R_3}V_3\rig…Preview
  15. Q15The output of an Op-amp adder is to be \(V_O = 3V_1 - 2V_2 + 5.5V_3\). If the value of the feedback resistor is \(30\text{ k}\Omega\), find…Preview
+Show 25 questions25 questions
  1. Q1What is a differential amplifier?Free
  2. Q2What is an OP-AMP?Free
  3. Q3Draw the circuit symbol of an op-amp.Free
  4. Q4List out any two characteristics of ideal OP-AMP.Preview
  5. Q5List out any two characteristics of practical OP-AMP.Preview
  6. Q6What are the different kinds of packages of OP-AMP?Preview
  7. Q7Define input offset voltage.Preview
  8. Q8Define CMRR of an op-amp.Preview
  9. Q9Define slew rate.Preview
  10. Q10What do you mean by virtual ground with respect to an op-amp?Preview
  11. Q11Mention any linear application of op-amp.Preview
  12. Q12Mention any non-linear application of op-amp.Preview
  13. Q13What is an integrator?Preview
  14. Q14Sketch the output of an integrator if the input is a sine wave.Preview
  15. Q15Sketch the output of a differentiator if the input is a square wave.Preview
  16. Q16What is a logarithmic amplifier?Preview
  17. Q17What is an active filter?Preview
  18. Q18What is a first order low pass active filter?Preview
  19. Q19What is a second order low pass active filter?Preview
  20. Q20Write any one application of logarithmic amplifier.Preview
  21. Q21What is a Digital to Analog convertor?Preview
  22. Q22What is an Analog to Digital convertor?Preview
  23. Q23Name any open loop application of an op-amp.Preview
  24. Q24What is a comparator?Preview
  25. Q25Name any one application of Schmitt Trigger.Preview
+Show 22 questions22 questions
  1. Q1Name four modes of differential amplifiers.Free
  2. Q2Draw the block diagram of op-amp.Free
  3. Q3Define slew rate of an op-amp.Free
  4. Q4Draw the pin configuration of IC741.Preview
  5. Q5Explain virtual ground concept with respect to op-amp.Preview
  6. Q6What are the assumptions made from ideal OP-AMP characteristics?Preview
  7. Q7Mention some of the linear applications of op–amps.Preview
  8. Q8Mention some of the non – linear applications of op-amps.Preview
  9. Q9How is an ideal Operational Amplifier different from a Practical Operational Amplifier? Explain.Preview
  10. Q10The gain of a buffer amplifier is unity. Explain.Preview
  11. Q11List the ideal parameters of an op amp and also write its values for 741 op- amp.Preview
  12. Q12How can you use an op amp to invert a signal?Preview
  13. Q13Draw the circuit diagram of a 3 input summing amplifier.Preview
  14. Q14Draw the circuit diagram of a subtractor.Preview
  15. Q15Draw the circuit diagram of a Logarithmic amplifier.Preview
  16. Q16Draw the circuit diagram of an anti logarithmic amplifier.Preview
  17. Q17Name any two types of Digital to analog converters.Preview
  18. Q18Draw the circuit diagram of binary weighted resistance DAC.Preview
  19. Q19Draw the block diagram of the counting Analog to Digital converter.Preview
  20. Q20What is a Zero Crossing Detector?Preview
  21. Q21How can you use an op amp as a comparator?Preview
  22. Q22What is a Schmitt trigger?Preview
+Show 18 questions18 questions
  1. Q1Draw and explain the block diagram of op-amp.Free
  2. Q2Draw the ac equivalent circuit of op-amp.Free
  3. Q3Write a note on ideal and practical characteristics of an op-amp.Free
  4. Q4Draw an inverting amplifier using op-amp and derive expression for its output voltage.Preview
  5. Q5Draw a non-inverting amplifier using op-amp and derive expression for its output voltage.Preview
  6. Q6Show how an operational amplifier can be used as an inverting adder.Preview
  7. Q7Show how an operational amplifier can be used as a subtractor.Preview
  8. Q8What do you understand by unity follower? Explain its gain term with a neat circuit diagram.Preview
  9. Q9Explain how an operational amplifier can be used as an integrator?Preview
  10. Q10Explain how an operational amplifier can be used as a differentiator?Preview
  11. Q11Show the circuit diagram by which we can obtain an output which is logarithm of input.Preview
  12. Q12Show the circuit diagram by which we can obtain an output which is anti-logarithm of input.Preview
  13. Q13Draw the circuit diagram, frequency response and expression for cut-off frequency for a first order RC low pass active filter.Preview
  14. Q14Draw the circuit diagram, frequency response and expression for cut-off frequency for a first order RC high pass filter.Preview
  15. Q15Draw a neat diagram of 4 bit R-2R ladder network DAC.Preview
  16. Q16Explain with neat circuit diagram working of a binary weighted resistance DACPreview
  17. Q17Explain Zero Crossing Detector with circuit diagram and waveforms.Preview
  18. Q18Show how an operational amplifier can be used as a perfect adder.Preview
+Show 12 questions12 questions
  1. Q1What is a differential amplifier? Draw four modes of differential amplifier?Free
  2. Q2Explain with a neat circuit diagram working of a dual input balanced output differential amplifier.Free
  3. Q3What is an Operational Amplifier? Write the properties of an Ideal Operational Amplifier and also draw its equivalent circuit.Free
  4. Q4Compare the following terms related to a practical Op-Amp in brief with respect to ideal op-amp a) Band Width b) Slew Rate c) Input Offset V…Preview
  5. Q5Explain virtual ground concept and also derive an expression for output of an inverting adder.Preview
  6. Q6With the circuit diagram show how to obtain an output which is logarithm of input.Preview
  7. Q7With the circuit diagram show how to obtain an output which is anti-logarithm of input.Preview
  8. Q8With the circuit diagram show how to obtain an output which is multiplication of two input signals.Preview
  9. Q9What do you understand by filters? Give its classification. Draw the circuit diagram, frequency response and expression for cut-off frequenc…Preview
  10. Q10With a neat diagram explain the working of 4 bit R-2R ladder network DAC.Preview
  11. Q11With block diagram and waveform explain the working of the counting Analog to Digital converter.Preview
  12. Q12With neat circuit diagrams and waveforms explain the applications of comparator.Preview